A number of improvements in methods to initiate and control the opening of a container have been described in the prior art. Various opening means in the form of perforations, slits, tear tapes or other techniques have been employed to produce a container that is convenient for the user to open without requiring external mechanical means.
One technique best illustrated in U.S. Pat. No. 7,789,291 and U.S. Pat. No. 7,810,641 incorporates cuts to facilitate tearing along a weakened line thereby providing an opening structure in the material. Due to the complete perforation of the material, this method is not suitable for use with food products or the like due to its lack of an effective barrier seal. U.S. Pat. No. 5,934,809, U.S. Pat. No. 6,173,554, U.S. Pat. No. 5,038,547 and U.S. Pat. No. 5,413,412 include perforations along with a layer of film forming material positioned over the line of weakness to insure the integrity of the seal. Inclusion of the film forming material requires an additional production step. A tear string embedded in the packaging material as shown in U.S. Pat. No. 5,470,419 and U.S. Pat. No. 5,203,935 also requires an additional step in the construction process. Another opening structure involves producing an integral tear tape by including parallel weakened lines in the material as best shown in U.S. Pat. No. 5,192,262. U.S. Pat. No. 5,167,606 includes lines of weakness in each laminate wherein the lines of weakness are offset to prevent premature tearing. U.S. Pat. No. 5,874,155 and U.S. Pat. No. 5,512,337 include multiple cuts or nicks on the surface of the material to facilitate tearing. In another technique, the line of weakness is produced by cutting through the material to a predetermined depth without cutting completely through as per U.S. Pat. No. 6,062,470 and U.S. Pat. No. 6,446,860. In this design, integrity of the moisture barrier is determined by the accuracy of the penetration created by the cutting tool.
As seen in the prior art, a need has been established for producing a container material with easy opening means and wherein a variety of techniques are currently utilized to achieve these results. A major concern with any technique for opening a container is product integrity, especially when related to food packaging. In some prior art examples, airtightness and leakability are not of great concern, wherein in food products, barrier integrity cannot be compromised. As such, a need for a material that will be both easy to open while providing product safety and integrity in a cost effective manner is needed.
The invention relates to multilayer composite materials constructed of a composition of 2 or more layers of paper, film or other tear compliant material which would be used to create a container. More specifically, the invention relates to multilayer composite material used to create a container that includes an area of weakness designed to allow the container to be opened along a controlled path in a manner that will retain container integrity while also being able to be manufactured in a cost effective and efficient manner.